Motor vehicle collisions (MVCs) are the leading cause of morbidity and mortality among adolescents, accounting for approximately one in three deaths among teens ages 16 to 19. The primary contributor to MVCs is driver inattention, which manifests as vulnerability to distraction. Yet, the relative contributions of young age and low driving experience to driving inattention remains unsettled and the general development of attention over the course of adolescence has received little study. The central hypothesis of this study is that driving attention and driving outcomes are predicted by age and driving experience through improvements in underlying cognitive mechanisms (general attention, speed of processing, and executive function). The long term goal of the research program is to explain the etiology of adolescent motor vehicle crash risk and translate findings to evidence-based interventions. In this longitudinal study, 220 adolescents will be enrolled across four groups of 55: 16 and 18 year olds with and without driving experience. The adolescents will perform general and driving based attention tasks, as well as cognitive function tasks at seven time points over 18 months. The combination of factorial and longitudinal designs will permit study of both the independent and joint effects of age and driving experience on driving attention over time. Multiple methods will be used to measure driving outcomes, including driving in a high fidelity driving simulator, self-report, and state crash records. Driving attention in the simulator will also be examined under several distraction conditions, because the presence of distractions challenges attention and is an important factor in MVC risk. Novel in-vehicle eye- tracking methodologies will track changes in driving attention development over 18 months. Four Specific Aims are proposed. Aim 1: Characterize the trajectory of driving attention development as a function of age and driving experience. Aim 2: Characterize the roles of age and driving experience in driving attention under varying levels of distraction. Aim 3: Examine the roles of underlying cognitive mechanisms (general attention, speed of processing, executive function) in driving attention development as a function of age and driving experience. Aim 4: Investigate how driving-specific attention development impacts driving outcomes. MVCs are burdensome and costly to society. With inattention as the primary contributor to MVCs, it is critical to gain a clearer understanding how driving attention develops during the riskiest developmental period for drivers: adolescence (ages 16 to 18). The findings of the proposed study have the potential to reduce MVCs by (a) shaping policy regarding optimal age and experience for licensure and limitations imposed on young drivers and (b) providing targets for interventions to improve public health.